HP 8340b User Manual

Fan Does
Not
Turn
Off
When
the
instrument
is
in
the
STANDBY
mode,
the
fan
should
not
run.
If
it
is,
the
fan
relay
(K1)
may
be
stuck,
or
the
+22V
supply
has
failed.
The fan
relay
solenoid is
energized when
the
instrument
is in
the
STANDBY
mode,
turning
the
fan
off.
If
the
power
to
the
relay solenoid
fails
(+22V
supply),
the
solenoid
de-energizes,
turning
the
fan
on.
INSTRUMENT CHECK LEDS REMAIN
ON
(4)
Instrument
check
LEDs
I
and
II,
located
on
the
front panel adjacent
to
the
[INSTR PRESET]
key,
indicate
the
results
of
self
test.
After switching
the
power
on
or
pressing
[INSTR
PRESET],
the
following
occur:
1.
Both
LEDs
turn
on.
2.
LED
I
turns
off
when
the
instrument
processor
determines
it is
operational,
and
has
verified
memory
and
the
peripheral interface
timer.
3.
LED
II
goes
off
when
the
processor
determines
that the
I/O
address
bus,
I/O
data
bus,
and
the
marker
ram
are
operating.
If
no
failure
occurs
during
self
test,
both
INSTR
CHECK
LEDs
go
off
after about
1
second.
If
either
remain
on,
the
instrument requires
service.
Refer
to
the
controller section
functional
group
for
trou¬
bleshooting
information.
NOTE:
Instrument
self
test
does
not
detect
all
instrument
failures.
If
you
suspect
a
problem
and
self
test
passes,
perform
the
service
diagnostic
routine,
SHIFT
M4
(see
FRONT PANEL
DIAGNOSTICS).
OVEN
ANNUNCIATOR
(5)
The
front
panel
OVEN
light
indicates the
status
of the internal
frequency standard.
When the
OVEN
annunciator
is
on,
the
frequency
is
more
than
100
Hz
from
10
MHz.
The
A51
assembly
10
MHz
reference
oscillator has
an
internal circuit
that
monitors
the
internal
oven
temperature.
When
the
oven
temperature
is
too
low,
the
HOVC line
is high
(greater
than
+15V).
When
the
oven
temperature
reaches
the
desired
point
(the
frequency
is
within
100
Hz
of
10
MHz),
HOVC
goes
low (less
than
+15V).
HOVC
is
sent
to
the
A59
digital
interface assembly
where
the
microprocessor
reads
it
and
determines when
to
turn
the
light
on
or
off.
The
oven
LED
is
located
on
the
A2 display
driver
assembly,
and
is
driven
by
the
A3 display
processor,
annunciator latch/driver.
The
LED
is
turned
on
by
the
instrument
processor.
The
processor
outputs
the
appropriate
bits
on
the
data
bus,
then
outputs
address
15:RO
to
latch
the data
bits.
If
the internal
10
MHz standard
is
used,
the
OVEN
annunciator
should
go
out
within
one-half hour
after
the
instrument
is
connected to
line
power.
If
the
annunciator stays
on,
the
instrument
requires
service.
If
the
instrument
is
using
an external
5
or
10
MHz standard,
the
OVEN
annunciator
indication
has
no
effect
on instrument
performance.
A-38 Assembly-Level
Service
Overall
Instrument
Troubleshooting
HP 8340B/41B

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English